1. Field of the Invention
The present invention relates generally to a mechanical mechanism, and more particularly to an elliptically moving mechanism.
2. Description of the Related Art
It is known that in some cases, it is necessary to cut an elliptical hole on a board material or an object such as awash sink of a washstand. U.S. Pat. No. 4,567,927 discloses an apparatus for automatically forming ovals. The apparatus enables a cutting tool to move in an elliptical path for cutting ovals.
The apparatus includes a support frame 10 composed of a pair of uprights 12 and a pair of cantilevered support arms 14. A support disk 26 is fixed by the cantilevered support arms 14. A ring 28 is suspended and pivotally rotatably disposed under the support disk 26. A first track 34 is disposed on the support disk 26. A second track 36 is supported by two uprights 38 and positioned above the first track 34. The second track 36 is perpendicular to the first track 34. A first bearing block 40 is slidably disposed in the first track 34 and a second bearing block 44 is slidably disposed in the second track 36. A trammel beam 56 is composed of an upper beam 56a and a lower beam 56b. The upper beam 56a is disposed on upper side of the support disk 26 and positioned between the first and second tracks 34, 36. The lower beam 56b is disposed under the support disk 26. The top and bottom ends of the first slide block 40 are respectively connected with the upper and lower beams 56a, 56b of the trammel beam 56. A tool-holding bracket 84 is mounted on the lower beam 56b. A cutting tool 92 is mounted on the tool-holding bracket 84. A threaded rod 108 is screwed with the tool-holding bracket 84 for driving the tool-holding bracket 84 and the cutting tool 92 to slide along the lower beam 56a. The ring 28 is drivable by an electrical motor 112, whereby the apparatus can provide an elliptical path 115 to cut an oval hole.
In the above apparatus, the cutting tool 92 is mounted under the support disk 26 for cutting the oval hole. Such arrangement has some shortcomings as follows:
First, the first and second tracks 34, 36 are up and down arranged so that it is necessary to use multiple cantilevered support arms and supports to fix the support disk 26 and the second track 36 respectively. Therefore, the entire support structure is quite complicated and hard to assemble. Moreover, the two tracks 34, 36 must be manufactured respectively. Also, the apparatus includes too many components. This leads to inconvenience in manufacturing the apparatus and the assembling cost of the apparatus is very high.
Second, the largest oval hole that can be cut by the apparatus cannot exceed the range of the support disk 26. As shown in FIG. 1 of the above patent, the length of the long axis of the elliptical path 115 is exactly the largest range that can be cut by the apparatus. This is because in the case that the lower beam 56b of the trammel beam 56, the tool-holding bracket 84 and the cutting tool 92 exceed the support disk 26, they will be obstructed by the uprights 12 from operating. Therefore, for cutting a larger oval hole, it is necessary to manufacture an even larger support disk 26 and ring 28 and longer tracks 34, 36. In this case, the entire apparatus will be huge and very heavy.